Synthesis of Pyridylphosphonates by Rhodium‐Catalyzed [2+2+2] Cycloaddition of 1,6‐ and 1,7‐Diynes with Diethyl Phosphorocyanidate

Abstract

The convenient and atom‐economical synthesis of substituted bicyclic pyridylphosphonates has been achieved by the cationic rhodium(I)/H8‐binap‐complex‐catalyzed [2+2+2] cycloaddition of 1,6‐ and 1,7‐diynes with diethyl phosphorocyanidate. These reactions may proceed via an azarhodacyclopentadiene intermediate in addition to the rhodacyclopentadiene intermediate.

Ni-catalyzed enantioselective [2 + 2 + 2] cycloaddition of malononitriles with alkynes

“…utilizing feedstock chemicals as starting materials to build diverse substitution patterns in a single synthetic step. [27][28][29][30][31][32][33][34] Correspondingly, an asymmetric catalytic version to assemble enantioenriched pyridines is a conceptually straightforward yet largely unsolved route. 35 There are a handful of examples reported but primarily limited to the construction of atropisomers of arylpyridines (Scheme 1D).…”

Transition metal-catalyzed [2 + 2 + 2] cycloaddition of nitrogen-linked 1,6-diynes: a straightforward route to fused pyrrolidine systems

“…58 The authors also reported an example of pyrrolidine-fused pyridine 80 preparation from 9a and diethyl phosphorocyanidate 79 (Scheme 28c). 59 Recently, Wan and co-workers described a general and efficient synthesis of 4,6,7-trisubstituted 2,3-dihydro-1H-pyrrolo [3,4-c]pyridines 83 by the [2 + 2 + 2] cycloaddition of corresponding dipropargyl amines 81 with ethyl 2-(hydroxyimino) acetate 82 employing a Rh(NBD) 2 BF 4 /MeO-biphep combination as the catalytic system in reuxing ethanol. This process tolerated various sensitive functional groups and generally provided 83 in good to excellent yields (Scheme 29).…”

Palladium-catalyzed annulative π-extension of o-halobiphenyls with o-chloropyridinecarboxylic acids to access azatriphenylenes

“…14 Furthermore, an efficient method for the synthesis of azatriphenylene derivatives through transition metal-catalyzed [2 + 2 + 2] cycloadditions of biaryl-linked diynes with nitriles was developed by the groups of Deiters 12 b and Tanaka. 15 Subsequently, photochemical cyclodehydrochlorination was used to produce azatriphenylene derivatives by the groups of Morin 16 a and Alabugin. 16 b In 2020, Zhao and coworkers synthesized azatriphenylene derivatives by double Suzuki coupling followed by the Scholl reaction.…”